I have a 88 firebird forumula 305 tbi.

Everything in my a/c / heater system works.

However... I got a small problem..

Lo
Med
^ Med high
O
High

this is a crappy rendition of our fan control on the dash.

When I am in Lo and High the fan blows the exact same, at a low speed

When I am in Med and Med High the fan blows the exact same, at a high speed

What could this be? Wrong relay? That is what I am guessing anyway.

 

The speed control resistors are under the hood in the heater box. Unplug it and make sure the wires for each speed are giving you full battery voltage. About 14 volts with the car running, 11 with the engine off. If the supplied voltage is o.k. I'd replace the resistor plate. Remove the 2 screws holding the plate down. There will be what appears to be different size springs on the other side of the plate.

The high running slow is odd as it is direct to the fan.

 

ill try that when I get home, and ill post voltage numbers

thanks for your input.

 

Well, didn't get to check the voltage, it snowed 8 inches in LAS VEGAS! So pretty cool day

 

Used to snow here in Michigan, but I've been dragging my feet on working in the cold garage on my project.

 

Where is this resistor plate?

 

Under the hood on the passenger side of the firewall. See the picture in post #2. There is the flat wire connector going into it. 2 screws holding it in.

 

they look fine, 4 pins on the top, and springs all coiled the the opposite sides of the posts on the back. it looks untouched and stock.

it is not my realy, i got a replacement one and worked the same way.

i am kinda stuck on this

to remind you, the low and high setting blow low. and the med and med high setting blow high. weird to me...

 

FIXED, it was the control on the dash, i replaced it with a junkyard part and BLAMO, fixed.